Frequently purchased together

It's tough to find a bag as warm as the Sierra Designs Nitro 0-Degree Down Sleeping Bag in the sub-three-pound range. The Nitro bag packs into an impressively small sack, and the Nitro's Flex construction provides comfort while allowing Sierra Designs to shave ounces.

Partial Flex construction on the exterior torso gives a bit of stretch between the shoulders and knees so you can sleep in a comfortable position yet still benefit from the efficient retention of body heat that a mummy shape provides

Ultralight jacket hood warms your head without adding ounces

Ultralight footbox vent adds a touch of airflow if you do get overly warm

Offset ultralight jacket zipper gives you just as much zipper as you need

Snag-free zipper tracks mean it isn't a struggle to get in and out of your bag

is this water resistant?

No, this is 800 fill down wrapped in 20D Nylon, it will lose some loft (and warmth) in humid environments, and if the bag gets wet, it will collapse and cease to insulate. The Fabric may bead the occasional water droplet, but not reliably.

Check out the Marmot EQ series for bags wrapped in the waterproof/breathable Membrain fabric, or the Mountain Hardwear Ultralamina series for Synthetic insulated bags that will retain warmth when wet.